Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Its main components are primary coil, secondary coil and iron core (magnetic core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc. According to the purpose, it can be divided into: power transformers and special transformers (electric furnace transformers, rectifier transformers, power frequency test transformers, voltage regulators, mining transformers, audio transformers, medium frequency transformers, high frequency transformers, impact transformers, instrument transformers, electronic transformers , reactor, transformer, etc.). Circuit symbols often use T as the beginning of the number. For example: T01, T201, etc.
1. According to the number of phases:
1) Single-phase transformer: used for single-phase loads and three-phase transformer groups.
2) Three-phase transformer: used to increase and decrease voltage in three-phase systems.
2. According to the cooling method:
1) Dry-type transformer: relies on air convection for natural cooling or adds fan cooling. It is mostly used for power consumption in high-rise buildings, high-speed toll stations and local applications. Small capacity transformers for lighting, electronic circuits, etc.
2) Oil-immersed transformer: relies on oil as cooling medium, such as oil-immersed self-cooling, oil-immersed air cooling, oil-immersed water cooling, forced oil circulation, etc.
3. Divided by use:
1) Power transformer: used to increase and decrease voltage in power transmission and distribution systems.
2) Instrument transformers: such as voltage transformers, current transformers, used in measuring instruments and relay protection devices.
3) Test transformer: It can generate high voltage and conduct high-voltage tests on electrical equipment.
4) Special transformers: such as electric furnace transformers, rectifier transformers, adjusting transformers, capacitive transformers, phase-shifting transformers, etc.
4. According to the winding form:
1) Double-winding transformer: used to connect two voltage levels in the power system.
2) Three-winding transformer: generally used in regional substations of power systems to connect three voltage levels.
3) Autotransformer: used to connect power systems with different voltages. It can also be used as an ordinary step-up or step-down transformer.
5. According to the core form:
1) Core transformer: a power transformer used for high voltage.
2) Amorphous alloy transformer: Amorphous alloy iron core transformer is made of new magnetic conductive material, and the no-load current is reduced by about 80%. It is a distribution transformer with ideal energy-saving effect, especially suitable for rural power grids and Developing areas and other places with low load rates.
3) Shell type transformer: special transformer for large current, such as electric furnace transformer, welding transformer; or power transformer for electronic instruments, TV, radio, etc.